Jessica Grose is a frequent Slate contributor and the author of the novel Sad Desk Salad. Follow her on Twitter.

These effects seem to peter out at some very high level—if you keep 5 percent of your income to yourself in order to have a little bit of discretionary spending, it won’t make you any less happy than you’d be if you pool 100 percent. But people who pool 80 percent are happier than those who pool 70 percent, and so on. People who keep it all to themselves are the least happy.

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McArdle cops to possible selection bias (if you don’t trust your spouse, you’re not going to be pooling money), but also notes that couples that don’t pool their earnings fight more about money. That’s not exactly what I found when I surveyed almost 6,000 Slate readers for my Home Economics project. I didn’t ask about happiness specifically, but I did ask about how often couples fought about money. There were negligible differences in the amount of fighting among couples that pooled all their money, some of their money, and none of their money.

But I did find that the longer couples were together, the more likely they were to pool their money, and I do think, based on my quantitative and qualitative look at these couples, that if you have children, keeping money entirely separate will lead to a lot of unnecessary stress. A child is the ultimate shared responsibility, and if you have to hash it out every time your kid needs new shoes, that’s going to create stress.

It’s also bad for women in heterosexual unions, because they end up paying for the lion’s share of kid expenses when couples keep their money separate. British sociologist Jan Pahl found that mothers were paying for 85 percent of their children's clothes and 78 percent of their child care and school expenses, while fathers paid for 73 percent of the family’s alcohol and 69 percent of their car expenses. Pahl writes:

We do not actually know whether payments for childcare come from joint accounts or individual accounts, but it is clear that typically women pay the costs of children, in the sense that they hand over the money or pay the bill. This does not matter if all the money coming into the household is pooled in a joint account to which both partners have access. However, it may be a very different story if the partners keep their ﬁnances separately and there is no expectation of sharing, either in income or spending.

That makes sense. As does the overall notion that couples that don’t pool any money are less happy than couples that do. But that blanket statement doesn’t account for the intricate nuances of how different kinds of couples manage their money and their relationships. I buy that pooling money is the best for a 40-year-old couple on their first marriage with two kids. But a couple of retirees on their second marriage, with no shared children? I’m not so sure.